In a significant expansion of the war on drugs, the United States has begun training an elite unit of counternarcotics police in Ghana and planning similar units in Nigeria and Kenya as part of an effort to combat the Latin American cartels that are increasingly using Africa to smuggle cocaine into Europe.

The growing American involvement in Africa follows an earlier escalation of antidrug efforts in Central America, according to documents, Congressional testimony and interviews with a range of officials at the State Department, the Drug Enforcement Administration and the Pentagon.

In both regions, American officials are responding to fears that crackdowns in more direct staging points for smuggling — like Mexico and Spain — have prompted traffickers to move into smaller and weakly governed states, further corrupting and destabilizing them.

The aggressive response by the United States is also a sign of how greater attention and resources have turned to efforts to fight drugs as the wars in Iraq and Afghanistan have wound down.

"We see Africa as the new frontier in terms of counterterrorism and counternarcotics issues," said Jeffrey P. Breeden, the chief of the D.E.A.'s Europe, Asia and Africa section. "It's a place that we need to get ahead of — we're already behind the curve in some ways, and we need to catch up."

The initiatives come amid a surge in successful interdictions in Honduras since May — but also as American officials have been forced to defend their new tactics after a commando-style team of D.E.A. agents participated in at least three lethal interdiction operations alongside a squad of Honduran police officers. In one of those operations, in May, the Honduran police killed four people near the village of Ahuas, and in two others in the past month American agents have shot and killed smuggling suspects.

To date, officials say, the D.E.A. commando team has not been deployed to work with the newly created elite police squads in Africa, where the effort to counter the drug traffickers is said to be about three years behind the one in Central America.

The officials said that if Western security forces did come to play a more direct operational role in Africa, for historical reasons they might be European and not American.

In May, William R. Brownfield, the assistant secretary of state for international narcotics and law enforcement, a leading architect of the strategy now on display in Honduras, traveled to Ghana and Liberia to put the finishing touches on a West Africa Cooperative Security Initiative, which will try to replicate across 15 nations the steps taken in battling trafficking groups operating in Central America and Mexico.

Mr. Brownfield said the vision for both regions was to improve the ability of nations to deal with drug trafficking, by building up their own institutions and getting them to cooperate with one another, sharing intelligence and running regional law enforcement training centers.

But because drug traffickers have already moved into Africa, he said, there is also a need for the immediate elite police units that have been trained and vetted.

"We have to be doing operational stuff right now because things are actually happening right now," Mr. Brownfield said.

Some specialists have expressed skepticism about the approach. Bruce Bagley, a professor at the University of Miami who focuses on Latin America and counternarcotics, said that what had happened in West Africa over the past few years was the latest example of the "Whac-A-Mole" problem, in which making trafficking more difficult in one place simply shifts it to another.